Phospholipase C (PLC) releases several proteins from the surfaces of myogenic cells in culture. At least one of these proteins may be involved in either the recognition phenomena preceding myoblast fusion or the fusion process itself. Chromatographic and electrophoretic techniques will be used to attempt to isolate the purify the protein(s). Electron microscopic examination of cells treated with PLC shows loss of certain specialized contact regions between myogenic cells. Whether the PLC-released protein is located in such contact regions will be investigated by electron microscopy of labeled antibody against the purified protein.